The use of filters in covered animal litter boxes has become increasingly popular. The cover conceals the animal waste and soiled litter from view and affords the animal privacy while using the litter box. The filter is typically replaceable and serves to absorb and/or neutralize litter box odors. When the filter loses its capacity to absorb odors, the pet owner generally removes and replaces the filter. However, some filters may only freshen and filter the air near the filter and thus, despite the filter, the litter box may still have stale and/or odor-filled air.